A woman who was perhaps Australia's biggest fan of the British royals has died at the age of 99, just days after receiving a birthday card from Prince Harry and his wife Meghan.

Daphne Dunne passed away peacefully on Monday, her family said.

She featured heavily in Harry's Australia trips and has pictures on Instagram of several encounters with the prince in recent years.

The widow said she'd had "a very special friendship" with the prince.

Days before her death, she received a birthday card from the royal couple.

"Dear Daphne, my wife and I send our warmest wishes to you on the occasion of your 99th birthday on Friday," the Duke and Duchess of Sussex wrote, according to Australian media, signing the card simply "Harry and Meghan".

Australia is a federal parliamentary constitutional monarchy, with the Queen as head of state.

Her Instagram account is full of pictures showing her with Prince Harry, with the caption to a 2015 photo saying "the very first time our eyes met, I knew this was the start of something very special".

'A special bond'
During the 2018 Australia visit by the prince and his wife, Ms Dunne was among the cheering crowds and again was picked out and greeted warmly by the two celebrity visitors.

The old lady was enthusiastic about the newly-weds, saying Meghan was "just what the prince needs".

The duchess told her at the time she was "so glad I got to meet you. Harry has told me all about you and your special bond, it's so lovely you came to see us, thank you".

Speaking afterwards, Ms Dunne said: "It was lovely to meet the duchess, Meghan. Harry is a wonderful man and I'm so happy he had found happiness, they both deserve the absolute world together."

Her first husband, Lieutenant Albert Chowne, died in 1945 during fighting in Papua New Guinea and was posthumously awarded the Victoria Cross, which Mrs Dunne was wearing when she first met Harry in 2015.

Her family wrote on Ms Dunne's Instagram account that "she was a truly special lady who will be greatly missed by so many".